Adjustable packing for hypodermic syringes



G. N. HEIN ADJUSTABLE PCKING FR HYPQDEMIC SYRIE-'EES Filed Aug. 26, 1924 Nov. 17 1925.

L I l wijle. j y v Patented Nov. 17, 1925.

UNITED STATES PATENT'oFFlcj-e.

Gunner: a'. HEIN, or sau` sancisce, entrenan.

A'n'Us'rABLn PACKING ron HYPODERMIC sYnNGns.

To all whom it may concer/n.'

Be it lrnown that I, GEORGE N. HEIN, a citizen of the United States, residing at the city and county of San Francisco and State of California, have linvented certain new and useful Improvements in Adjustable Packings for 1-Iypode'rmic Syringes, of which the following is a specification.

This invention relates to means for adj usting the packing of piston in a hypodermic syringe without ren'iovingthe piston from muuu uw emu.

The objects of the invention are, among others, to provide means whereby an elastic piston is capable of adjustment so that a snug fit can be had between the periphery of the same and the barrel wall; to provide a construction whereby a snugly fitting piston is adapted for readily releasing from the barrel wall should the same adhere or stick thereto; to provide a structure wherein the end wall of the barrel and one-portion of the packing retaining head are fashioned to afford co-acting surfaces, the latter when in engagement reducing to a minimum `the relative axial movement between the .packing retaining head and the barrel end wall enabling the desired adjustment of the packing to be obtained on a relative rotary movement being imparted to the piston and barrel.

With the above mentioned and other objects in view, the invention consists in the novel construction and combination of 'parts hereinafter described, illustrated in the accompanying drawings, and set forth inthe claims hereto appended, it being understood that various 'changes vin the form, proportion, size and minor details of construction within the scope of the claims maybe resorted to without departing from the spirit or sacrificing anypof the advantages of the invention. j

To more fully comprehend the invention, reference is directed to the accompanying drawings, wherein 1 is a view partly in vertical section of the preferred embodiment of my construction.

Fig. 2 is a transverse sectional view on line 2-2 of Fig. 1.

Fig. 3 is a vertical section of a barrel and syringe illustrating a1 modified form of packing retaining-head.

Fig. 4 is a further modified form of retaining head @ed adjusting meehansm? and appntauon med August 26, 1924. serial No. 734,208.

. Fig, 5 is a still further modified form illustrating spring means associated with the stem of the retaining head.

In thedrawings, wherein like characters of reference designate corresponding' parts, 1 indicates a cylindrical piston mounted for reciprocation and axial rotation within a tubular barrel 2, the same being ar Conventional hypo'dermic syringe barrel. The barrel is formed with an end wall?)` having discharge opening 4, and in the embodiment illustrated there is detachably secured at the end 3 of the barrel provide-d with the outlet a lshell or 'cap 5 having a tubular discharge nozzle 6 registering with the outlet 4. The disclosure is illustrated with the base 7 of a hypodermic needle 8 positioned on the discharge nozzle '6. One end of the piston 1 is provided with any suitable form of finger grip 9, and the other end is domed or rounded as at 10, and threaded thereinto v is vthe stem 11 of a headed packing retaining member 12, the latter being formed with a radial curved surface disposed oppositely to the dome or curved surface 1,0 of the piston end.

In the embodiment illustrated in Fig. 1, the retaining head or member 12 has extended from its outer face projections 13 which are adapted for contact with projections 14, and the inner surface of the end wall 3 clearly illustrated in Figs. 1 and 2, and mounted between the member 12 .in the domed end 10 olf-'the piston 1, is an elastic packing or washer 14 of a size, when not expanded, to lightly contact with theinner wall surface of the barrel 2, and the eXpansion of which, due to its elasticity, being controlled by the relative adjustment of the member 12 and end 10. The adjustment stated above may be accomplished without withdrawing the' piston from the barrel by first forcing the piston fully within the barrel until the projections 13 engage with projections 14, thereafter relative axial movement in opposite directions ibeing imparted to the piston and barrel causing greater or less tension to be placed on the packing; expanding and contracting the same as desired.

Fig. 3 illustrates the outer face of the retaining member 12, beingfashioned in substantially conical formation as at 15 to frictionally engage corresponding surface '16 formed on the inner face of the end wall 3 ef the barrel 2.,

In the modifications illustrated in Figs. l and 5, the piston disclosed is of reduced diameter to that illustrated in Fig. 1, and is guided in an opening disposed centrally of a closure member 17 threaded to the upper end of the barrel 2 as at 18.

In these respective modifications, the headed packing retaining member is formed with the bevelled peripheral walls 19 and 20, and a shell guiding boss 21 is Idisposed between the head 22 and the threaded stem 23. The boss 21 forms a guide for a thimble 24 loosely mounted on the stem 23 and between the lower peripheral edge of which and the upper surface of the head 22 is mounted an elastic packing washer 25.

In Fig. 4, the upper portion of the thimble 2st is provided with a friction surface 26 to engage onl the upward movement of the piston within the barrel 2 with the bevelled surface of the closure member 17 and transmit the resistance through the packing 25 to the head 22 to cause said head to move with the barrel when relative axial rotation in opposite directions is imparted to the piston and barrel.

In Fig. 5, the thimble 2l is formed with an annular seat 27 on which rests the lower end of a sleeve 28 surroundingl the stein 25:3, and in this case the upper end of the sleeve 28 is bevelled as at 29 to provide a surface for frictionally engaging the bevclled surface. of the member 17 when the piston is drawn its full length upwardly in the barrel. In this construction, a spring 30 coiled about the threaded stem 23 bears against the upper end of the thimble 2li and normally retains the same snugly in Contact with the elastic packing 25.

It will be observed that the disclosure illustrated in Figs. 1, 2, and 3 of the drawings is adjustable in the syringe only after the piston has completed its full discharge stroke, and the disclosure in Figs. l and 5 enables the adjustment of the elastic packing when the piston is at either end of its stroke.

I-Iaving thus described my invention what lI claim and `desire to protect by Letters Patent of the United States is 1. A hypodermic syringe including a barrel substantially closed at one end providing a discharge port, a piston mounted for reciprocation and axial lrotation therein, a packing retaining head threaded into the end of the piston, said piston and retaining head being provided with opposing walls affording a chamber' within which a packing is positioned, said walls extending in opposite directions outwardly from each other, an elastic disk washer packing positioned within the chamber with its inner portion held between the piston end and retaining head walls and with its periphery lying parallel to the barrel surface and free to flex between the outer portions of the piston and retaining head walls, and means for affording a resistance to the head to retain the saine substantially stationary on the imparting of relative rotary movement between the barrel and piston whereby the pressure of the packing against the barrel wall may be varied.

2. A hypoderinie syringe including a barrel provided with a substantially closedend formed with recesses on its inner surface and provided with a discharge port, a piston mounted for reciprocation and axial rotation therein, a packing retaining head threaded into the end of the piston, said piston and retaining head being provided with co-operating surfaces curved from the center radially in opposite directions, a relatively thin elastic disk washer packing positioned between the piston end and retaining head with its periphery lying parallel to the barrel surface, Said retaining head 011 its end provided with projections for reception in the recesses in the barrelend wall to hold the same substantially stationary on the imparting of relative rotary movement between the barrel and piston whereby the pressure of the packing against the wall barrel may be varied.t

8. A piston for hypoderinic syringes including va stem, a head carried by one end thereof and movable to and from the stein saone-n N. nain. 

